Republican presidential front-runner Donald Trump has made an embarrassing slip-up at his final rally before the big-prize primary contest in New York.

The brash billionaire businessman was about to deliver prepared remarks lauding New York values when he mistakenly mentioned the name of convenience store chain 7-Eleven instead of 9/11 - the September 11 2001 terror attacks.

Campaigning in Buffalo, he said: "It's very close to my heart because I was down there, and I watched our police and our firemen down at 7/11, down at the World Trade Centre right after it came down, and I saw the greatest people I've ever seen in action."

Mr Trump has repeatedly invoked the September 11 attacks as he has campaigned across his home state. He paid his first visit to the National September 11 Memorial & Museum earlier this month.

He drew an estimated crowd of more than 11,000 to the First Niagara Centre hockey arena, but the event was interrupted by protesters.

About a dozen young people locked arms and sat down on the floor of the arena shortly after Mr Trump took to the stage, forcing authorities to carry several out.

Buffalo police said they arrested six people, mainly for disorderly conduct and trespassing. They said no arrests were made inside the arena, but 21 people were ejected from the event.

Mr Trump predicted a big win in Tuesday's New York primary, telling his supporters that "no New Yorker can vote for" rival Ted Cruz, who "doesn't represent what we need".

He is also predicting he will secure the 1,237 delegates he needs to lock up the nomination ahead of this summer's party convention, despite some recent stumbles when it comes to making sure supportive delegates can attend.

Victories in New York could help quiet critics who have questioned both Mr Trump's and Democrat front-runner Hillary Clinton's strength as White House favourites. Each has suffered losses in recent contests that emboldened their rivals, though they still lead in delegate counts and are favoured in New York.

Mrs Clinton, who represented the state as a senator for eight years, spent the final hours of campaigning trying to drive up turnout among women and minorities, her most ardent supporters.

"We're not taking anything for granted," she said, after greeting workers at the Hi-Tek Car Wash & Lube in Queens.

Her campaign was more blunt in outlining the state of the Democratic race. Mrs Clinton's campaign manager Robby Mook declared the primary effectively over, saying rival contender Bernie Sanders faced a "close to impossible path to the nomination".

With the Democratic contest becoming increasingly tense, Mr Mook said the Vermont senator had to choose whether he wanted to stay on a "destructive path" that could hurt the party's eventual nominee.

Mrs Clinton has accumulated 1,758 delegates to Mr Sanders' 1,076. Those totals include both pledged delegates from primaries and caucuses, as well as superdelegates, the party insiders who can back the candidate of their choice regardless of how their state votes.

Heading into Tuesday's primary, Mr Sanders needs to win 68% of the remaining delegates if he hopes to clinch the Democratic nomination. It takes 2,383 to win.

On the Republican side, Mr Trump leads with 744 delegates, ahead of Mr Cruz with 545 and John Kasich with 144. It takes 1,237 to win the party nomination.

Mrs Clinton's campaign sees New York as a make-or-break moment for the Democratic race. A loss in her adopted home state would be a devastating political blow but a big win would bolster her delegate lead over Mr Sanders and put her closer to becoming the first woman nominated for president by a major political party.

Mr Sanders has rattled off a string of wins in recent primaries and caucuses. But unless he can topple Mrs Clinton in a state like New York, where 247 Democratic delegates are up for grabs, he faces increasingly limited opportunities to change the trajectory of the race.

While polling shows Mrs Clinton with a comfortable lead in New York, Mr Sanders held out hope for a closer race.

"This is a campaign on the move," he told thousands gathered along the waterfront in the New York City borough of Queens. "This is a movement getting the establishment very, very nervous."